path: root/drivers/usb/class/usbtmc.c

/**
 * drivers/usb/class/usbtmc.c - USB Test & Measurment class driver
 *
 * Copyright (C) 2007 Stefan Kopp, Gechingen, Germany
 * Copyright (C) 2008 Novell, Inc.
 * Copyright (C) 2008 Greg Kroah-Hartman <gregkh@suse.de>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * The GNU General Public License is available at
 * http://www.gnu.org/copyleft/gpl.html.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/kref.h>
#include <linux/mutex.h>
#include <linux/usb.h>
#include <linux/usb/tmc.h>


#define USBTMC_MINOR_BASE	176

/*
 * Size of driver internal IO buffer. Must be multiple of 4 and at least as
 * large as wMaxPacketSize (which is usually 512 bytes).
 */
#define USBTMC_SIZE_IOBUFFER	2048

/* Default USB timeout (in milliseconds) */
#define USBTMC_TIMEOUT		10

/*
 * Maximum number of read cycles to empty bulk in endpoint during CLEAR and
 * ABORT_BULK_IN requests. Ends the loop if (for whatever reason) a short
 * packet is never read.
 */
#define USBTMC_MAX_READS_TO_CLEAR_BULK_IN	100

static struct usb_device_id usbtmc_devices[] = {
	{ USB_INTERFACE_INFO(USB_CLASS_APP_SPEC, 3, 0), },
	{ 0, } /* terminating entry */
};
MODULE_DEVICE_TABLE(usb, usbtmc_devices);

/*
 * This structure is the capabilities for the device
 * See section 4.2.1.8 of the USBTMC specification for details.
 */
struct usbtmc_dev_capabilities {
	__u8 interface_capabilities;
	__u8 device_capabilities;
	__u8 usb488_interface_capabilities;
	__u8 usb488_device_capabilities;
};

/* This structure holds private data for each USBTMC device. One copy is
 * allocated for each USBTMC device in the driver's probe function.
 */
struct usbtmc_device_data {
	const struct usb_device_id *id;
	struct usb_device *usb_dev;
	struct usb_interface *intf;

	unsigned int bulk_in;
	unsigned int bulk_out;

	u8 bTag;
	u8 bTag_last_write;	/* needed for abort */
	u8 bTag_last_read;	/* needed for abort */

	/* attributes from the USB TMC spec for this device */
	u8 TermChar;
	bool TermCharEnabled;
	bool auto_abort;

	struct usbtmc_dev_capabilities	capabilities;
	struct kref kref;
	struct mutex io_mutex;	/* only one i/o function running at a time */
};
#define to_usbtmc_data(d) container_of(d, struct usbtmc_device_data, kref)

/* Forward declarations */
static struct usb_driver usbtmc_driver;

static void usbtmc_delete(struct kref *kref)
{
	struct usbtmc_device_data *data = to_usbtmc_data(kref);

	usb_put_dev(data->usb_dev);
	kfree(data);
}

static int usbtmc_open(struct inode *inode, struct file *filp)
{
	struct usb_interface *intf;
	struct usbtmc_device_data *data;
	int retval = -ENODEV;

	intf = usb_find_interface(&usbtmc_driver, iminor(inode));
	if (!intf) {
		printk(KERN_ERR KBUILD_MODNAME
		       ": can not find device for minor %d", iminor(inode));
		goto exit;
	}

	data = usb_get_intfdata(intf);
	kref_get(&data->kref);

	/* Store pointer in file structure's private data field */
	filp->private_data = data;

exit:
	return retval;
}

static int usbtmc_release(struct inode *inode, struct file *file)
{
	struct usbtmc_device_data *data = file->private_data;

	kref_put(&data->kref, usbtmc_delete);
	return 0;
}

static int usbtmc_ioctl_abort_bulk_in(struct usbtmc_device_data *data)
{
	u8 *buffer;
	struct device *dev;
	int rv;
	int n;
	int actual;
	struct usb_host_interface *current_setting;
	int max_size;

	dev = &data->intf->dev;
	buffer = kmalloc(USBTMC_SIZE_IOBUFFER, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	rv = usb_control_msg(data->usb_dev,
			     usb_rcvctrlpipe(data->usb_dev, 0),
			     USBTMC_REQUEST_INITIATE_ABORT_BULK_IN,
			     USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT,
			     data->bTag_last_read, data->bulk_in,
			     buffer, 2, USBTMC_TIMEOUT);

	if (rv < 0) {
		dev_err(dev, "usb_control_msg returned %d\n", rv);
		goto exit;
	}

	dev_dbg(dev, "INITIATE_ABORT_BULK_IN returned %x\n",